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The shorthead drum Larimus breviceps has an important role in the subsistence of local communities. However, studies addressing the trophic ecology of this species are still scarce. Here we present further information on the trophic ecology and ecomorphology of L. breviceps, including dietary analyses, carbon and nitrogen stable isotopes compositions (δ13C and δ15N), and morphometric measurements on a seasonal basis. Specimens were captured in the Northeastern Brazil from February to November 2017 by the local artisanal shrimp fisheries. A total of 46 individuals (27 juveniles and 19 adults) were randomly subsampled for ecomorphological analysis. Significant differences in the ecological attributes between ontogeny were found for peduncle and body flatness indexes. A total of 479 stomachs of L. breviceps were analyzed. The fish total length ranged from 6.3 to 19.2 cm. Nine prey categories were defined for L. breviceps. Sergestidae shrimps were the main prey. The diet composition from the multivariate technique of non-metric multidimensional scaling ordination displayed a different pattern for juveniles and adults. A subsample of 40 individuals (dry season = 20; rainy season = 20) were selected for stable isotope analysis. Mean values of δ13C and δ15N were different by size in the dry season. This information improves the general knowledge and ecological data on bycatch species, as well as may give support to management initiatives, potentially associated to trophic models, or may be considered into the design of Bycatch Reduction Devices (BRD), taking into account the current paradigm of the Ecosystemic Approach to Fishery (EFA).

Despite being an important source of wealth and food security for many countries, most of the small tuna stocks in the Atlantic Ocean and Mediterranean Sea remain unassessed. In this study, we summarized the current state of knowledge of this group of species reviewing the information available on life history parameters, stock structure, historical catches, size frequency distributions and current knowledge of stock status. In relation to the life history parameters, data are overall scarce and mainly missing in the Eastern Atlantic where small tunas are relevant in small-scale fisheries. From the 27 defined stocks, only 11 have been quantitatively assessed. From those, the Northwest wahoo and the Southeast little tunny stocks may be experiencing overfishing, deserving priority management attention. Length-based rather than catch-based methods showed a more promising applicability for small tunas, although representative length distributions from the catch are scarce for some stocks. Historical catch time series for small tuna are still incomplete, however, the last two decades are the most accurate and could be considered in future assessment methods. The gaps of knowledge related mainly to life history parameters and historical catches are the main reason why most of these stocks remain unassessed and unmanaged.

Large pelagic sharks are distributed throughout all of the oceans and are caught as bycatch in pelagic longline fisheries worldwide. In the southern Atlantic Ocean, more than a dozen shark species are caught by the Brazilian tuna longline fleet. This study compiles information of the main shark species caught by the Brazilian tuna longline fishery in the southwestern and equatorial Atlantic Ocean. Catch and effort data of 14,860 longline sets from the Brazilian chartered tuna longline fleet, between 2004 and 2010, were analyzed. The blue shark Prionace glauca was the main shark species captured by this fishery. Shark catches showed contrasting trends during the study period: the silky (Carcharhinus falciformis) and the oceanic whitetip (C. longimanus) sharks catch increased up to 2008 and then declined, while mako sharks (Isurus spp.) showed an opposite trend. Effort for the Brazilian longline fishery had a higher concentration from 10°N to 30°S and from 20°W to 40°W. High values of catch per unit effort of southwestern and equatorial Atlantic Ocean sharks were heterogeneously distributed and, although elasmobranchs were caught over most of the longline fishing range, only blue sharks were caught in all areas. In the southern Atlantic Ocean, high fishing effort zones overlap significantly with some nursery areas, especially for the oceanic whitetip shark, indicating that these areas are at a direct risk from the industrial longline fishery.